Heat exchanger attachment for hot water heaters



March 26, 1957 J. A. MARTIN 2,785,653

HEAT EXCHANGER ATTACHMENT FOR HOT WATER HEATERS Filed Feb. 4, 1953 IN VEN TOR.

8 2/ J5/m A. MART/N ATTORNEYS 2,786,653 1C3 Patented Mar. 26, 1

HEAT EXCHANGER ATTACHMENT FOR HOT WATER HEATERS John A. Martin,Minneapolis, Minn.

Application February 4, 1953, Serial No. 335,095

4 Claims. (Cl. 257-137) This invention relates generally to anattachment for converting conventional hot water heaters to efiicientspace heaters for small farm buildings and the like and is animprovement on my co-pending application, Serial No. 294,825, filed June21, 1952, and entitled, Combination Hot Water and Space Heating Unit.

While the attachment for converting hot water heaters to efiicient spaceheaters disclosed in my above identified co-pending application hasproved very successful and efficient, the attachment conversion devicedisclosed in the instant application has proved to be considerably moreeflicient and is more universally applicable to a wide variety ofdifferent styled conventional hot water heaters.

It is an object of my present invention to provide a novel and highlyefiicient heat exchanger attachment for conventional hot water heatersparticularly constructed to maintain close heat transfer associationbetween the air traveling through the heat exchange chamber and the heatexchange surface of the hot water tank.

It is another object to provide an attachment for conventional hot waterheater tops to convert the same to an efficient heat exchanger and spaceheating unit which provides a heat exchange chamber overlying the top ofthe tank in direct contact therewith and confined to the area of theupper portion of the tank surface while providing a tortuous pathparticularly constructed to maintain close heat transfer associationbetween the circulating air and the heat exchange surface of the tankexposed thereto.

More specifically, it is an object to provide a plurality ofsubstantially concentric bafiles having circulating openings formed inthe lower edge portions thereof adjacent the tank top to permit air totravel from one passage to another adjacent the top surface of the hotwater heater tank.

These and other objects and advantages of this invention will more fullyappear from the following description made in connection with theaccompanying drawings wherein like reference characters refer to thesame or similar parts throughout the several views, and in which:

Fig. l is an exploded side elevational view of my new heat exchanger;

Fig. 2 is a bottom perspective view of the heat exchanger attachment;

Fig. 3 is a central vertical sectional view showing the heat exchangermounted in operative position on a hot water heater tank top; and

Fig. 4 is a schematic view showing diagrammatically the heat exchangepassages and by directional arrows the air flow circulation pathstherethrough.

As illustrated in the accompanying drawings, I show a conventional hotwater heater tank 6 surrounded on the sides by an annular insulationjacket 7 and an outside protective casing 8. The tank 6 has a centralupstanding conduit 9 and is of generally conventional design.

An annular casing member 10 is mounted at the top of the protectivecasing 8 and has an abutment collar 11 fixed thereto in upwardly spacedrelation to the lower edge thereof. The lower depending edge portiondisposed below the collar 11 is of slightly smaller diameter than theupper portion of easing 8 and is received within said upper casingportion 8 with the collar abutting the top peripheral edge thereof. Apair of openings 12 and 13 are formed on opposite sides of the annularcasing member 10 and a deflector hood 13a is disposed outside thedischarge opening 13. A shell 14 having a depending annular skirt 14a ofsubstantially the same diameter as the upper portion of the tank 6 tofit therearound, as best shown in Fig. 3, is provided and is positionedwithin the annular casing member 10 and defines a heat exchanger chamberunder said shell 14. Inlet and outlet openings are formed in the upperdome-shaped top of shell 14 and conduits 15 and 16 are respectivelyconnected therewith to interconnect said openings with the respectiveopenings 12 and 13 formed through the easing 10. Suitable sealing pads15a and 16a are respectively provided on the outer ends of conduits 15and 16 to sealingly engage the portions of the casing 10 respectivelysurrounding openings 12 and 13.

The chamber defined within the shell 14 is subdivided by a pair ofconcentrically disposed bafiles in the form of cylindrical segments 17and 18 providing an annular passage therebetween with the inner segment18 defining a central discharge chamber therewithin. The lower edges ofthe baflles 17 and 18 have serrated portions, as best shown in Figs. 2and 3, and the lower edges of said batlles are positioned relative toeach other and to the skirt 14a of shell 14 to engage the outsidesurface of the top of tank 6, as best shown in Fig. 3. The portion ofbaffle 17 disposed in inwardly opposed relation to the inlet conduit 15has a straight lower edge which remains in substantially sealed contactthroughout its length with the tank top and divides the air flowing inthrough said conduit 15, as indicated by the arrows in Fig. 4. The airtravels around the outer annular passage in contact with the tank topand passes inwardly therefrom through the serrated side portions of saidbaffle 17. The inner baffle 18 is serrated around the entire lowerperiperal edge thereof and maintains contact between the flowing air andthe top surface of the tank as said air flows through the openingsbetween the teeth of the serrations into the central discharge chamber.The air is forced to flow back behind the imperforate portion of bafile17 since the circumference of thebafile 18 is substantially shorter thanthe circumference of the bafile 17 and the air flowing through the sideser' rated portions of bafiie 17 has a greater volume than can passthrough only the lateral side portions of the inner baffle 18.

A pair of spaced delivery guiding plates 19 are fixed between the spacedend extremities of the baffles 17 and 18 with the inner ends thereofdisposed adjacent the ends of said inner cylindrical segment 18, as bestshown in Fig. 2, to form a discharge passage communicating with thedischarge conduit 16 and forcing the air to flow through the desiredtortuous path in contact with the top surface of tank 6 to remove heattherefrom with a high degree of eificiency.

A blower 20 is mounted'on the outside of easing section 10 and deliversair into the heat exchanger chamber in contact with the top of tank 6,and said air is discharged through the outlet conduit 16 after beingwarmed by contact with said top of tank 6. Suitable insulation isprovided above the shell 14 and is designated by the numeral 21. Acasing cover 22 may be provided in overlying relation to said insulationand, in the form shown, this casing cover is the same cover normallyused on the conventional hot water heaters and has a dependingattachment flange portion adapted to receive the upper 3 marginalportion of the annular casing member 10, as best shown in Fig. 3.

The following is a description of the operation of my improved heatexchanger attachment for converting hot Water heaters to space heatingunits. After the conventional cover 22 and insulation has been removedfrom the hot water heater, the entire shell with the cylindrical bafllesfixed therein is placed on the top of tank 6 in direct contacttherewith, with the depending skirt 14a engaging the outer peripheralportion of said tank top, and forming a heat exchanging chamberthereabove. The blower 20 draws air from the room and delivers the sameinto said chamber through inlet conduit 15. The air initially isdirected against the imperfonate section of the outer cylindrical baffle17 and the flow is divided and passes around the sides of the top oftank 6 within the area confined by the depending skirt portion 14a andis forced through the openings of the serrated lower edge of the sideportions of said bafile 17 into the intermediate annular heat exchangingchamber between the two substantially cylindrical bafiies 17 and 13. Dueto the fact that the periphery of the inner bafile 13 is substantiallyshorter than the periphery of the outer baffle 17 and therefore the openarea through which the air must of necessity pass, through theserrations formed in the lower edge of said inner bafile 13, issubstantially less adjacent the sideportions thereof, the air is thuscaused to circulate around the entire outer periphery of said innerbafile 18 and finally pass into the discharge chamber in contact withthe tank top and out through the discharge conduit 16 and is deflecteddownwardly by the deflector plate 13a.

It will be seen that l have provided a relatively simple, yet highlyeflicient, attachment for conventional hot water heaters to convert thesame into a heat exchanger for efficiently heating a room such as a milkhouse or the like. The communication openings formed by the serrationsaround the side portions of the outer baflle 17 and the serrationsformed in the lower edge portion of the inner baffle 18 cause the air tofiow from one chamber to another in contact with the tank top to moreeffectively remove the heat therefrom.

It will, of course, be understood that various changes may be made inthe form, details, arrangement, and proportions of the parts withoutdeparting from the scope of this invention which, generally stated,consists in the matter shown and described herein and set forth in theappended claims.

What I claim is:

l. A heater exchanger attachment for a hot water portions with the upperedges thereof in substantially sealed contact relation with the insidesurface of the cover shell and positioned relative to each other in amanner to provide a plurality of heat transfer passages in heat exchangecontact with the tank top, the lower marginal edge portions of saidbaflie members having a plurality of: openings formed therein to permitcirculation of the air between said passages and maintain contactbetween the circulating air and the heat exchange surface of the hotwater heater tank top, said cover shell having inlet and outlet meansformed therein in communication with said chamber, and means for causingcirculation of air through the passages in said chamber.

2. A heat exchanger unit comprising a generally domeshuped heat exchangesurface with a cover shell disposed in spaced relation to the heatexchange surface with the outer portion thereof sealingly interconnectedwith said surface to form a heat exchange chamber between said shell andsaid surface, a plurality of generally concentric baffles of segmentalcylindrical shape disposed in substantially sealed contact at theirupper edges with said shell and extending downwardly therefrom to engageportions of the heat exchange surface and form a plurality of heatexchange passages in contact with said heat exchange surface, saidbafiles extending the full distance between shell and said surface buthaving openings only in the lower marginal edge portions thereof toafford communication between said passages whereby turbulence of theflowing air is produced by the openings in said baffles extending only apart of the distance 'between the shell and the heat exchange surface,said shell having laterally disposed inlet and outlet openingscommunicating with said passages but communicating with each other onlythrough said passages, and means for causing circu lation of air throughsaid openings and said passages.

3. The structure set forth in claim 2 and the edges of said battles incontact with said heat exchange surface being serrated to provide theintercommunication openings between said passages adjacent the heatexchange surface.

4. The structure set forth in claim 2 and said serrated openings beingof greater dimension adjacent said heat exchange surface than they areremote therefrom to increase the heat exchange contact of the flowingair with said surface.

References Cited in the file of this patent UNITED STATES PATENTS163,443 Barrows May 18, 1875 282,567 Richardson Aug. 7, 1883 312,678Vaughan Feb. 24, 1885 336,392 Converse Feb. 16, 1886 l,0l3,050 Orr Dec.26, 1911 2,175,307 Peck Oct. 10, 1939 2,244,831 Drichta et a1. June 10,1941

